Last N Observations Query Track

Submitting WG/Project/Implementer Group

Justification

The lastn query meets the common need for searching for the most recent or last n=number of observations for a subject.

Examples where this query could be used:

Fetch the last 5 temperatures for a patient to view trends

Get the most recent lab results for patient

Fetch the last 3 results for all vitals for a patient

The $lastn operation is has been introduced as part of FHIR STU3, but has not yet undergone yet been widley implemented. This goal of this track is encourage server implementation of the operation, uncover implementation issues, and help evaluate if similar operations would be useful for other clinical resources such DiagnosticReport.